Since Elizabeth Taylor was so successful and iconic in her later career — in Cat on a Hot Tin Roof and Butterfield 8, to name a couple — it's easy to forget that she was a teen star. Her first role was in There's One Born Every Minute (1942), when she was only 10 years old.
Sophie Marceau - 14 years old in "la boum"
and
Natalie Portman - 12 years old in Léon